Fish oil poses problems, researchers charge - Agricultural Research Human Nutrition Center on Aging at Tufts University; Food and Drug Administration unconvinced of health benefits

Nutrition Health Review, Spring, 1991

Fish Oil Poses Problems, Researchers Charge

The Food and Drug Administration is not convinced of the fish oil "miracle." It has recently disallowed all health claims for the capsules.

There is good reason for caution, according to researchers at the Agricultural Research Human Nutrition Center on Aging at Tufts University. "Feeding of fish oil has been a classic method for inducing vitamin E deficiency in laboratory experiments," says M. Meydani, a researcher at the Human Nutrition Center.

The reason may be linked to the fact that fish oil is more vulnerable to oxidation than most other fats, so more of the antioxidant vitamin is required for protection. Without it, oxidized fats themselves become oxidizing agents, setting off a chain reaction. The process is witnessed whenever rapidly spoiled fish exudes a putrid, "deal fish" odor.

In animals and people, unchecked fat oxidation can damage critical molecules inside cells, including DNA.

Manufacturers of fish oil capsules find it necessary to add synthetic antioxidants and vitamin E to preserve the oil's shelf life. The precautions are not enough, say Tufts University experts. The additives do not provide sufficient protection.

Other researchers have noted that there is reason to believe fish oil supplements can depress the immune system's response to infection. Researchers at the Center say they have determined that fish oil reduces the production of T-cells and other lymphocytes by at least 63 percent.